Dielectric and ferroelectric properties of CoCr2O4 nanoceramics

Abstract

CoCr2O4 nanoceramics are prepared by sol–gel auto combustion method. Synchrotron X-ray diffraction analysis affirms the single-phase pristine cubic structure with space group [Formula: see text]. Debye–Scherrer method estimates the crystallite size of main intense peak to be [Formula: see text][Formula: see text]nm. Prominent bands obtained in infrared spectra at 448 and 599[Formula: see text]cm[Formula: see text] are due to metal–oxygen stretching bond present at tetrahedral and octahedral sites. Dielectric parameters decrease as frequency increases from [Formula: see text] to [Formula: see text][Formula: see text]Hz that can be interpreted by Maxwell–Wagner-type interfacial polarization. Complex impedance spectra (Nyquist plot) reveal arc like behavior, which is mainly due to intergrain (grain boundary) resistance that also exhibits conducting nature of the nanoceramics. Weak ferroelectricity is mainly associated with the partial reversal of the polarization. Leakage current behavior follows the Ohmic and Child square law. Electron conduction process was interpreted by space-charge limited current (SCLC) mechanism. Leakage current behavior observed in cobalt chromite nanoceramics is mainly attributed to the oxygen vacancies.